On 28 December 2023, the Treasury and the IRS issued a notice of proposed rulemaking regarding whether a debt instrument is worthless for US federal income tax purposes under Code section 166 (the “Proposed Regulations”). The Proposed Regulations would update the standards under Treas. Reg. § 1.166-2 used to determine when debt instruments held by regulated financial companies or members of a regulated financial group are conclusively presumed worthless.